I've used those modules (0,25mW, 433MHz), with limited success...
They're supposed to make a link at up to 200m, but I only got about 25m,
when using a helical-antenna. When swithing to a whip-antenna (both home
made) I got about 50m though (outside).

I had a problem with the modules, as their BW was about 10KHz, and I was
using a digital encoder/decoder running at about 5KHz. I never made it
working, but used a DTMF-encoder/decoder instead, which worked great.

I just looked at there web page and they are the same units as
radiometrix (http://www.radiometrix.co.uk) and LPRS
The wide band 418mHz units I've had very good results from
The 173mHz not as good but still not bad
--
Peter Cousens
email: .....peterKILLspam.....cousens.her.forthnet.gr
snailmail: Peter Cousens, karteros, Heraklion, Crete, 75100, Greece,
phone: + 3081 380534, +3081 324450 voice/fax

After Bill Gates announced to the world that he was Microsoft,
his wife was asked to comment. She said that as his wife, she
had been the first to notice this problem